Abstract: In comparison with the traditional two-dimensional tumor cell culture, the three-dimensional tumor spheroid culture can not only provide with an in vivo-like growth environment for tumor cells, but also maintain maximum cell activities. Therefore, the three-dimensional tumor spheroid culture is widely used in oncology research. In particular, the three-dimensional tumor cells retain the material and structural basis of the microenvironment of tumor in vivo, which is closer to the actual physiological environment, allowing it to be an ideal in vitro model for evaluating the tumor treatment response and drug resistance in tumors. This review summarizes the mechanisms of drug resistance in three-dimensional tumor cells, especially those induced by the morphology and microenvironment of three-dimensional tumor spheres, and puts forward the problems existing in the current three-dimensional tumor cells model, as well as the future development direction.